Because of new insights into the physical chemistry and pathophysiology of bile acids and other nutrient milieu in the small intestine and new bioengineering approaches to more efficient resins, the development of enormously improved bile acid adsorbents is now possible. In a Phase I program, Merix has developed a class of cationic ion exchange resins which are new compositions of matter. These new resins have higher bile salt binding capability than current resins, are highly swellable, and have readily accessible interior binding sites. By coupling these new resins with methods for increasing the fraction of sites which participate in binding bile salt molecules, we expect to achieve a 10-fold lowering of sorbent dosage requirements relative to present therapeutically used cholestyramine and colestipol resins. This will minimize the inconvenience and unpleasant side effects of resin therapy and will lower its cost, making it more widely available and prescribed for use in lowering serum cholesterol levels.